Abstract
The running-in of cylinder liner-piston rings (CLPRs) is the most important process that must be performed before a marine diesel engine can be operated. The quality of running-in directly affects the reliability of a CLPR. The surface texture of a CLPR has been proven to significantly affect its lubrication performance. In this study, the tribological behavior of a CLPR during running-in is investigated. Three types of surface textures are generated on the CLPR via laser processing: dimple texture on piston rings, groove texture on cylinder liners, and co-texture on both sides. Subsequently, a series of tests are performed on a slice tester. A load of 300 N (1.64 MPa) is applied, and two speeds (50 and 100 rpm) are adopted. The CLPR running-in quality is characterized based on three parameters, i.e., the friction coefficient, contact resistance, and wear topography. Experimental results show that, compared with a non-textured surface, the three types of surface textures mentioned above improved the friction performance during running-in. The lubricant supply capacity of the dimple texture on the piston ring, as a mobile oil reservoir, is stronger than that of the groove texture on the cylinder liner serving as a static oil reservoir. By contrast, the wear resistance of the dimple texture, as a movable debris trap on the piston ring, is weaker than that of the groove texture on the cylinder liner, which serves as a static debris trap. It is demonstrated that the co-texture combines the advantages of dimples and groove textures. Compared with non-textured surfaces, the friction coefficient decreased the most at 100 rpm (44.5%), and the contact resistance improved the most at 50 rpm (352.9%). The coupling effect provides the surface with improved running-in quality by optimizing the tribological performance, particularly at the dead center. This study provides guidance for the tribological design and manufacturing of CLPR in marine diesel engines.
Highlights
The cylinder liner-piston ring (CLPR) wear process comprises different stages, in which running-in is inevitable prior to steady wear [1]
The lubricating oil was injected into CLPRs at a rate of 1 mL/min, which was significantly greater than the actual consumption
It was observed that group A had a greater average friction coefficient than the textured CLPR under all operating conditions and durations of the experiments; this indicated that the texture of this structural parameter had anti-friction properties
Summary
The cylinder liner-piston ring (CLPR) wear process comprises different stages, in which running-in is inevitable prior to steady wear [1]. Surface texturing is a new surface treatment technology originating from bionics It can yield desirable surface properties by machining a certain topography on friction pair surfaces under oil lubrication. Surface texturing is effective in improving the lubrication characteristics of CLPRs [15,16,17]. Mohamad et al [22] discovered that cylinder liner oil grooves can be used efficiently to maintain the hydrodynamic effect, and optimum surface texturing might substantially reduce friction losses. The cylinder liner or piston ring is typically regarded as a separate component when a surface texture is applied. Texture patterns were generated on the surfaces of the cylinder liners and piston rings via laser processing. The amount of friction reduction, oil film characteristics, and morphological features of the co-textured surface were analyzed and compared with those of non-textured and singletextured surfaces
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